Silent DIY Air Compressor with Auto-Switch

I have posted an article about silent home-made airbrush compressor before. It was a free translation of article I have found at one of the resources from eastern Europe I use. Then I decided to build (diy air compressor) myself and since I have found few tips to make this compressor more comfortable to use with less maintenance effort.

Here is the schema:

As you noticed this does not include the electric drawing as it is exactly the same as in my earlier post. On top of that I’ve added a pressure switch which needs its own power cord.

So how does it work?

The air from fridge compressor is pumped to receiver (tank). To keep the air clean I’ve used air filter (petrol filter) on the input of the compressor. Tank (receiver) works as capacitor (collecting the air) and we can use any empty gas tank or fire extinguisher that can hold the pressure around 100 psi. Some people are using 2L or 5L plastic bottles which I wouldn’t recommend as it can’t hold that pressure. Here is the tank I have used.

When we consider the pressure in the tank, the air is as well pressing in reverse on compressor with that pressure and this can cause the compressor to overheat or even destroy it after some time. So I recommend to use check valve (non-return/one-way valve) between compressor and receiver.

Check valve allows air to flow only one way.

Do not forget what I mentioned in my earlier article about compressor that fridge compressor use to spit some oil on its output, and I’ve recommended to use transparent tank that you could see all the spat oil in it and from time to time empty it. Here we go further by using oil-humidity collector-reducer (professionally called Air Filter / Regulator / gauge – Ampro AR2654 3/8-Inch Air Filter, Regulator) before the check valve, that means there will be no need to empty the receiver :).

Very useful part is a manometer on your tank. You can watch the pressure inside while configuring the air pressure switch.

Automatic Pressure switch

A really scary word for someone who builds his own compressor. Don’t worry there is nothing scary about it. Setting it up is also very easy.

Simple explanation of its function:

It will switch compressor off when we get maximum pressure in the tank and then switch it back on when pressure gets down to the minimum level. On the schema it is connected between tank and check valve because we have to set it up according to pressure from the tank. Technology is very simple and genius at the same time. The compressor is connected to electricity through this switch. When there is no pressure the circuit is closed and compressor is switched on pumping the air into tank. But when pressure is raising up pressure switch gets to a certain point when the pressure gets to the maximum and the circuit and compressor goes off. While we’re working the tank is loosing the air and at one moment the pressure is too low to keep the circuit of pressure switch opened so compressor will go back on again; so your compressor works less with better efficiency and it won’t overheat and hopefully will live longer.

The pressure switch is very useful thing because it saves not only our compressor but reduces our electricity bills as well (Air Pressure Switch for Single-Stage and Dual-Stage Air Compressor – 1/4in).

How to set-up the pressure switch?

This switch has two threads under the hood. All you have to do is to set the position of screw females to set the maximum and minimum level of the pressure. First turn on the compressor and notice the pressure on manometer when it goes off; after that, loose some air to notice the pressure when it goes back on. Now pick one of the threads and screw the female screw halfway in. Turn it on and watch the pressure again for both positions.

What we have to find that is which particular thread is responsible for switching it on / off.

That is all from theory. Let’s do some manual work. I won’t write about building process, you can read it here because it is similar except for few things that are not really important. All depends on your skills.

Here is some of the stuff I have used.

As case I’ve used an old speaker box.

And some pictures of final product “Silent almost maintenance free airbrush compressor”. I hope that not only airbrushists will enjoy this post…

I didn’t even finish the case. I wanted to put a grill or net on both sides to keep it practically opened for good air flow. For now the cooling is fine as it is still opened :). It is working fine and the most important thing – it makes noise like fridge (almost unnoticeable).

Related

Please ! Do not forget to tell people to have the compresor in the fridge , Extracted to remove the freon, so the flourocarbons do not escape into the atmosphere, and chew up more of the Ozone. Here in the states it is a $10,000.00 fine if you are caught venting freon! Please Keep It Green !!

Hi Goming_se! I didn’t get exactly what are you asking for. If you want to make it at home you don’t need my permission, just follow the instructions in this article. :) And what exactly do you want to download?

Goming_se

thanks for the responses I’m trying terebut reading your articles, I mean download a video on how to disassemble the compressor refrigerator

Alright Goming_se, Thanks for your interest! If you want some instructions about disassembling the compressor you may take a look at this http://airbrushdoc.com/tipstricks/homemade-airbrush-compressor/ , but I don’t have any video about it. The one in my sidebar is from Youtube and it is about “how to open the compressor” (If compressor is working fine I would not recommend to do that). If you want to download that video from Youtube you may use application called JDownloader (it’s free, just google it).

Narain Panchal

Good morning ! please explain me how to adjust auto switch screw for cut off / on. In the picture there are two screw, one is with small spring and other with big spring. which screw is for cut off and which is for on. what is the position of both screw before adjusting them, fully loosed or tight. thanks. try understand my english because i am maharastrian.

Hey Narain, Thanks for your question. Don’t worry, your English is fine and I understood exactly what you were asking for. I added picture, so you will see better when I explain everything.

First of all you should have your tank filled up with the air, that when you will loose some air you will see when the switch goes on. The small spring “number 1 on the picture” is called differential spring and it sets the difference between “on” and “off” cut points. When you start setting your switch you should fully tight the differential spring (1). Then tight up a bit the big spring (2) and loose the air from tank and watch the pressure on your gauge (manometer). With this spring you will set the “on” pressure you need (minimal pressure). Only when you done with you minimal pressure setting go back and loose up the differential spring (1) which is there to set up the cut “off” pressure (maximal pressure you need). I hope that my answer will help you somehow. I admit that it is not clear from the article how exactly it has to be set. Sorry goes to everyone ;)

Jay

HI Sergej, really good article (Y)…. I was just wondering why did you but the regulator before the tank and not after disel filter or before outbut to airbrush? Is it just to filter the air coming from the compressor so u wouldnt get any spill inside the tank or is there other reasons as well?

And if the regulator is before tank and you want to change the output pressure is there a any delay?

Hi Jay, Yes, the main reason to have regulator there is to prevent any spill inside the tank, otherwise you will have to unmount it from time to time and empty it.

I don’t think that position of the regulator has any impact on the delays in pressure changes.

Thanks for your questions Cheers

Bob

Great article, Just a small point, the pressure switch you show doesnt have an unloader valve to release the pressure in the pipework between the compressor output and the tank. If the compressor is a LST (low starting torque) type it wont be able to start against high pressure. I highly recommend using a HST/HBP compressor, tDanfoss SC__ G models make excellent air compressors.

Hello Antish, The one we used here is from old van compressor but I don’t remember exactly. The best and probably the easier to find is old, used fire extinguisher. The most common size in airbrush air compressors that you can buy in airbrush shop have from 2 to 3L. If you going to do art illustrations with many details you don’t need more but if you want to paint bigger I’ll go for bigger size tank and off coarse more powerful compressor or using more compressor in one build.

jackC

Hello Sergej,

I am trying to convert a fridge compressor into a vacuum pump to try vacuum bagging. Is it very similar to your compressor and is it just everything attached to the vacuum pipe rather than outlet pipe? Do you have plan/schematic for doing such a thing? And where would you put the pressure switch in the pipes? And how would you set the pressure switch to come on when vacuum is lost (such as if there is a leak?)

Hi JackC, sorry for later repply, I don’t have such schematic but you have give me a bug into my head. I’ll think about it and will let you know… just give me some time ;)

ChrisCssr

Hello, I’ve just happened to read this article and it really interested me. I want to build an air compressor now!! Here you posted a photo of some stuff that you have used (air pressure switch, gauges, fittings etc…). I was wondering what fittings you have used! By any chance is it possible to mention the type of fittings used please?

Hi Chris, To be hones I used everything I found in my garage and I just found the ones that fitted to each other, but I promise to check it again and find out what exactly it is (probably by the size). I’ll post it as soon as possible Cheers